Agroforestry Services: Nitrogen  Management: Hay  Minor Global Crop  Staple Crop: Protein

Butterfly pea is essentially a plant of the humid and subhumid tropical lowlands at elevations from sea level to around 1,600 metres[310 ]. It is also grown as an annual in warm temperate areas[310 ]. It grows best in areas with an annual rainfall in the region of 1,500mm, but it has a reputation for drought tolerance in the seasonally dry tropics (with 500 - 900 mm annual rainfall) and can probably survive with as little as 400mm annual rainfall[310 ]. Its annual mean temperature range is 19 - 28°c and it has survived moderate frost damage in the subtropics (at a latitude of 26°S)[310 ]. Plants can succeed on a variety of soils as long as they are well-drained, but prefer a fertile, friable soil, growing poorly on infertile sandy soils if they not fertilized[310 ]. It does well on heavy clay soils[310 ]. Prefers a position in full sun[310 ]. It succeeds within a pH range of 5.5 - 8.9[310 ]. Butterfly pea is one of the few herbaceous legumes well adapted to heavy clay soils in the subhumid to semi-arid tropics and the only one with potential in irrigated pasture mixtures on these soils[310 ]. Early growth of the plant from seed is rapid in warm moist conditions. Growth of established plants is mostly from the apices of the main axis and axillary branches; very few new shoots arise from ground level[310 ]. Growth is more or less continuous in the humid tropics, or with irrigation in other hot regions. Individual plants may live for several years and grow into large vines if undisturbed[310 ]. In the seasonally dry tropics and in cool regions, growth is limited by lack of moisture or low temperatures. Leaves are shed in response to these stresses and top growth may be killed by frost or fire. However, recovery during the following growing season is usually good[310 ] Butterfly pea competes fairly well with weeds once established and can cover the ground in 4 - 6 weeks when sown at a population of 4 plants per square metre. Establishment may be a problem on fertile soils if sown with a vigorous companion grass or oversown into an existing pasture. It combines better with tussock than stoloniferous grasses in mixed pastures. The location of its growing points at the ends of the main branches makes it susceptible to frequent low cutting as well as to continuous heavy grazing[310 ]. Flowers are cleistogamous but a small level of outcrossing occurs. Time to flowering can range from 7 - 11 weeks. Subsequent flowering flushes overlap pod maturation from the previous flush, and they continue throughout the year in frost-free regions. At higher latitudes in the tropics, there is usually a peak at the end of the wet season and again at the end of the cool season, if moisture is available. Pods mature in 8 - 10 weeks after flowering and shatter readily once fully dry. There is considerable variation in the size of flowers and leaflets[310 ]. The plant is propagated by seed and readily self- propagates and spreads under favourable conditions by seed thrown vigorously from the dehiscing dry pods. Seed is also spread in cattle dung[310 ].Inoculation of butterfly pea seed with rhizobia is not usually necessary; but, if it is required, broad spectrum cowpea inoculum should be used[310 ]. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[200 ]. Climate: tropical. Humidity: semi-arid to humid. Carbon Farming - Cultivation: minor global crop. Management: hay.

Carbon Farming

• Agroforestry Services: Nitrogen  Plants that contribute to nitrogen fixation include the legume family – Fabaceae.
• Management: Hay  Cut to the ground and harvested annually. Non-destructive management systems maintaining the soil organic carbon.
• Minor Global Crop  These crops are already grown or traded around the world, but on a smaller scale than the global perennial staple and industrial crops, The annual value of a minor global crop is under $1 billion US. Examples include shea, carob, Brazil nuts and fibers such as ramie and sisal.
• Staple Crop: Protein  (16+ percent protein, 0-15 percent oil). Annuals include beans, chickpeas, lentils, cowpeas, and pigeon peas. Perennials include perennial beans, nuts, leaf protein concentrates, and edible milks.